Abstract
Endolysins are phage-encoded enzymes implicated in the breaching of the bacterial cell wall at the end of the viral cycle. This study focuses on the endolysins of Deep-Blue (PlyB221) and Deep-Purple (PlyP32), two phages preying on the Bacillus cereus group. Both enzymes exhibit a typical modular organization with an enzymatically active domain (EAD) located in the N-terminal and a cell wall binding domain (CBD) in the C-terminal part of the protein. In silico analysis indicated that the EAD domains of PlyB221 and PlyP32 are endowed with peptidase and muramidase activities, respectively, whereas in both proteins SH3 domains are involved in the CBD. To evaluate their antimicrobial properties and binding specificity, both endolysins were expressed and purified. PlyB221 and PlyP32 efficiently recognized and lysed all the tested strains from the B. cereus group. Biochemical characterization showed that PlyB221 activity was stable under a wide range of pHs (5–9), NaCl concentrations (up to 200 mM), and temperature treatments (up to 50 °C). Although PlyP32 activity was less stable than that of PlyB221, the endolysin displayed high activity at pH 6–7, NaCl concentration up to 100 mM and the temperature treatment up to 45 °C. Overall, PlyB221 and PlyP32 display suitable characteristics for the development of biocontrol and detection tools.
Highlights
Bacteriophages or phages are viruses that infect bacteria
After the phage multiplication using the host replication and translation machineries, the virion progeny is released in a lytic process causing the host death
Endolysins do not possess a signal sequence to be transported through the plasmidic membrane
Summary
Bacteriophages or phages are viruses that infect bacteria. They are extremely diverse regarding their morphology, genomic material, and lifestyle [1]. The most common phage lifestyles encountered are the lysogenic and lytic cycles. After receptor recognition and DNA injection, temperate phages coexist within their host, either integrated in the chromosome or as independent plasmid-like molecules, in a state called prophage [2,3]. Endolysins do not possess a signal sequence to be transported through the plasmidic membrane. They rather cooperate with another protein, the holin, to achieve cell lysis [6]. At the end of the lytic cycle, endolysins accumulate in the cytoplasm until holins have oligomerized and formed pores in the membrane, allowing endolysins to reach the PG layer, in a tight time regulated process [7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
